Dr. Young (after having lost $1000) leaves angrily and comes back after several more days.

Dr. Young: “My eyesight has become weak — I can hardly see anything!!!!”
Dr. Geezer: “Well, I don’t have any medicine for that so, Here’s your $1000 back.” (giving him a $10 bill)
Dr. Young: “But this is only $10!”
Dr. Geezer: “Congratulations! You got your vision back! That will be $500.”

Moral of story — Just because you’re “Young” doesn’t mean that you can outsmart an “old Geezer”